Re: [PATCH v3 3/3] mtd: cfi_cmdset_0002: Use chip_ready() for write on S29GL064N

[Tokunori Ikegami <ikegami.t@gmail.com>]

Hi,

On 2022/03/16 3:51, Miquel Raynal wrote:
> Hi Tokunori,
>
> ikegami.t@gmail.com wrote on Wed, 16 Mar 2022 01:56:07 +0900:
>
>> As pointed out by this bug report [1], the buffered write is now broken on
>                                         , buffered writes are now broken
>
>> S29GL064N. The reason is that changed the buffered write to use chip_good
>> instead of chip_ready.
> "This issue comes from a rework which switched from using chip_good()
> to chip_ready(), because <explain the difference here>."
>
> [please note I am just trying to understand what the root cause is,
> please rephrase if I'm wrong].
Fixed by the version 4 patches.
>
>> One way to solve the issue is to revert the change
>> partially to use chip_ready for S29GL064N since the way of least surprise.
> s/since the way of least surprise//
Fixed by the version 4 patches.
>
>
>> [1] https://lore.kernel.org/r/b687c259-6413-26c9-d4c9-b3afa69ea124@pengutronix.de/
>>
>> Fixes: dfeae1073583("mtd: cfi_cmdset_0002: Change write buffer to check correct value")
>> Signed-off-by: Tokunori Ikegami <ikegami.t@gmail.com>
>> Tested-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
>> Cc: Miquel Raynal <miquel.raynal@bootlin.com>
>> Cc: Richard Weinberger <richard@nod.at>
>> Cc: Vignesh Raghavendra <vigneshr@ti.com>
>> Cc: linux-mtd@lists.infradead.org
> I think you can get rid of all the above Cc: tags and just copy all 3
> of us + the mailing list when sending your v4.
Fixed by the version 4 patches.
>
>> Cc: stable@vger.kernel.org
>> ---
> Please also include a Fixes/stable tag in the patch before (2/3) to explain
> that both patches are required in order to fix the issue and the current patch alone won't apply.
>
> You should mention that with a nice comment below the three dashes ("---") in patch 2/3 as well.
>
>>   drivers/mtd/chips/cfi_cmdset_0002.c | 10 ++++++++++
>>   1 file changed, 10 insertions(+)
>>
>> diff --git a/drivers/mtd/chips/cfi_cmdset_0002.c b/drivers/mtd/chips/cfi_cmdset_0002.c
>> index 8f3f0309dc03..fa11db066c99 100644
>> --- a/drivers/mtd/chips/cfi_cmdset_0002.c
>> +++ b/drivers/mtd/chips/cfi_cmdset_0002.c
>> @@ -867,10 +867,20 @@ static int __xipram chip_good(struct map_info *map, struct flchip *chip,
>>   	return chip_check(map, chip, addr, &expected);
>>   }
>>   
>> +static bool __xipram cfi_use_chip_ready_for_write(struct map_info *map)
>> +{
>> +	struct cfi_private *cfi = map->fldrv_priv;
>> +
>> +	return cfi->mfr == CFI_MFR_AMD && cfi->id == S29GL064N_MN12;
>> +}
>> +
>>   static int __xipram chip_good_for_write(struct map_info *map,
>>   					struct flchip *chip, unsigned long addr,
>>   					map_word expected)
>>   {
>> +	if (cfi_use_chip_ready_for_write(map))
>> +		return chip_ready(map, chip, addr);
>> +
>>   	return chip_good(map, chip, addr, expected);
>>   }
>>   
> This is much more understandable.
>
> Vignesh, perhaps it would be better to provide a way for manufacturers
> to overload certain callbacks instead of applying quirks like this in
> the code. But that will come in a second time of course.
>
>
> Thanks,
> Miquèl